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CVE PROGRAM SOURCE RECORD4.8 Medium

CVE-2026-40594

pyLoad: Session Cookie Security Downgrade via Untrusted X-Forwarded-Proto Header Spoofing (Global State Race Condition)

Description

pyLoad is a free and open-source download manager written in Python. Prior to 0.5.0b3.dev98, the set_session_cookie_secure before_request handler in src/pyload/webui/app/__init__.py reads the X-Forwarded-Proto header from any HTTP request without validating that the request originates from a trusted proxy, then mutates the global Flask configuration SESSION_COOKIE_SECURE on every request. Because pyLoad uses the multi-threaded Cheroot WSGI server (request_queue_size=512), this creates a race condition where an attacker's request can influence the Secure flag on other users' session cookies — either downgrading cookie security behind a TLS proxy or causing a session denial-of-service on plain HTTP deployments. This vulnerability is fixed in 0.5.0b3.dev98.

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

pyload pyload

  • < 0.5.0b3.dev98affected

References